A dynamic speaker is generally constructed, as shown in FIG. 1, with a yoke Y attached to a permanent magnet M producing a powerful, radial magnetic field, a center retainer S concentrically holding a movable coil (voice coil) V in the air gap or central opening thereof, and a cone housing H attached to the opposite side of the yoke Y for movably supporting a vibrating plate (a cone) C therein, with the smaller diameter portion being secured to the voice coil and the larger diameter portion being movably connected to the divergent opening of the housing H.
In the conventional speakers the cone tends to be relatively thin for reducing the entire mass and to be relatively large in size for producing a larger output, which inevitably brings about some undesirable defects such as: (a) thinness of the cone makes the same inferior in stiffness or rigidity and incapable of effectively using the entire surface thereof; (b) bending or flexion of the cone makes the input wave-form difficult to be transmitted intact to the output; (c) inside loss is relatively large, which is an unavoidable disadvantage caused by the light-weight and low-stiffness of the cone; and (d) a combination of three speakers for high, medium and low sound areas is employed for keeping constant sound characteristics regardless of the frequencies, which combination however being too delicate and unsuitable for mass production of the cones.
This invention is aimed at the provision of dynamic speakers excellent in frequency characteristics ranging over a wide sound area, and highly efficient in reproducing real sound wave-form regardless of the relatively small size of the cone, by giving the same an appropriate stiffness with some novel structural techniques.